Yea I tried that I didnt like the way it looked If I decide to do something In It has to be correct . It is a 300 +watt power supply from an old dell computer. I custom built a metal box it has 6 120 v ac plugs 4 usb charging ports molex plugs sata power and others

Dummy load just needs to draw a few watts from the 5v rail. It doesn't have to be specifically 5 watts (10 ohm at 5v). So long as the ohm rating doesn't draw enough current to over-watt the resistor you're fine. Try to draw 2-10 watts and you'll be fine.